Apparatus for the transmission of current pulse combinations, particularly for teletyping



Oct. 27, 1953 o. MOSER 2,657,260

APPARATUS FOR THE TRANSMISSION OF CURRENT PULSE COMBINATIONS,PARTICULARLY FOR TELETYPING Filed Dec. 10, 1952 Patented Get. 27, 1953APPARATUS FQR THE TRANSMISSION ()F CURRENT PULSE COMBINATIONS, PAR-TICULARLY FOR .TELETYPING Otto Moser, Bern, Switzerland A plicationDecember, 10, 1952, SerialNo. 325 ,163 In Switzerland December 14, 1951'7 Claims. (Cl. 178-17) My invention relates toapparatus for thetransmission of currentpulse combinations, particu-- larly forteletyping.

fS uch apparatus have a group .of selectively actuable setting means,consisting in teletypee writers essentially ofakeyboard withindividually operable keys, for selecting a code combinationcorresponding to the particular message character to betransmitted. -Anumber of pulse control members and correlated to the respective settingmeans or keys. The pulse control members may consist of revolvable camdiscs that are firmly mounted ona common shaft or on different shaftsdriven by a motor. The pulse control cams become selectively effectiveto control an electric contact device .for transmitting tothecornmunication channel. the trains of electric pulses .correspondingto the various code combinations.

It has been proposed'to provide the pulse-controlling cam .discs ,insuch apparatus with a lateral cam groove rather than with aperipheralcam configuration, the. lateral cam grooves of the respectiveldiscsbeing differently shaped in accordance with the particular codecombination assigned to each disc. Each cam disc coacts with anindividual feeler which is normallyoutside the groove and enters it onlywhen the pertaining setting means or keyis being actuated. Theparticular. feeler thus placed into cam engagement then acts as a camfollower during one full cam revolution. and is thus caused to oscillatein a rhythm corresponding, to the code combination assigned tov theselected message 'character to be transmitted; and the electric contactdevice then closes and opens a circuit to issue corresponding electricpulses. An apparatus of this type, in contrast to those operating with acam contour on the exterior cam periphery, has the advantage of a morereliable operation due to the fact that it eliminates contact-bouncingand reduces contact wear by the constrained guidance of the feelers,thus avoiding the pulse distortions resulting from such trouble.However, the pulse control appa-' ratus with lateral cam grooves asheretofore pro posed incur the drawback of imposing highly exacting.requirementgupon the accuracy of the cams, thus involving considerablemanufacturing Although,'in teletypewritersystems, slight de-' fectionsof .the .pulse combinations are usually corrected in the central orexchange stations, there are cases where the communication channel It isan object of myinvention to provide an apparatus for the transmission ofcurrent-pulse combinations that affords within its own mechanism acorrection of deficiencies that may be due tojinaccuracies in design orassembly of the pulsecontrol cams.

While the invention is hereinafter described with reference to apparatusin teletypewriters operating basically in the manner explained above,the invention is also applicable to any other devices for the selectivetransmission'of code combinations in which a mechanical switchingmember, moving back and forth between two positions under control by aselectively actuated setting means, controls an electric pulse contactin accordance with the particular pulse combination to be issued.

According to my invention, I provide such a transmitting apparatus withtwo revolvable cam discs which are driven at constant speed during theoperating period of the pulse control means. Each cam disc has camflanks mutually spaced on the cam'periphery in accordancewith the pulseperiods of, the pulse combination ,to be issued. Two movable switchinglevers, engaging the respective cam discs, are moved between active andinactive positions due to the revolution of the cam discs, and therebychange the contact condition of the above-mentioned electric pulsecontact, one lever effectinga change in one sense and the other lever inthe opposite sense. I

further provide the apparatus with locking means I which, under controlby the pulse-wise reciprodoes not pass through such a station. Thisapadapt them to any parti'cular conditions of {the communicationchannel.

eating switching member, alternately lock one of the two levers andsimultaneously release the other lever, the phasing of the releasingoperation being such that each lever, shortly after its release, reachesone of the cam flanks and hence can then move to its active positionthus switchingfthe'pulse contact. 7 V

The foregoing 1 and more specific objects and features of my inventionwill be apparent from the following description of the embodimentexemplified by the drawing, in Which a pulse-com-' binationjtransmittingapparatus for a teletypewriter is schematicallyshown' in a perspectiveView.

isschematically shownat it. Firmly mounted ona shaft 53 are anumber ofpulse control-discs,

one for each key, of-which again only one is illustratedfat M. Likeall-others, the disc M is provided-witha lateral cam groove 2'? whosecam contour is designed in accordance with the one pulse combinationassigned to the particular pulse control disc. .Eachpulsecontroldisccooperates with'a 'feeler member designed as, a lever ii which istiltable about a pivot H and whose free end carriesa feelerzpin 152..Feelermember ii has a bias in the counterclockwise direction;

also causes a start-stop drive (not shown) for revolving the shaft 53 tobe started. During the revolution of the pulse control disc i l, thefeeler 'pin 42 is caught and held in the groove 27 until a fullrevolution of disc hi is completed. During the revolution of the pulsecontrol disc I i, the

feeler member 5i oscillates as its feeler pin fol lows the configurationof the cam groove. An arm 41a of feeler member 4! then causes amechanical switching member 43 to also oscillate between two endpositions in accordance with the pulse combination to be transmitted.The switching member as is pivotally mounted at l2 so that itsoscillations occur in a plane parallel to the plane of illustration. Theswitching member 43 is common to all feeler members of the apparatus.

During the revolution of the pulse control disc I4, another shaft i8 isalso revolving at constant speed. The shaft i8 may be driven from shafti5, and for this purpose may, for instance, be coupled with shaft is ormay form an extension thereof. Shaft 13 carries two cam discs 5! and 58.Each of these cam discs is equipped with cam flanks 57a or 55a which arespaced from each other on the periphery of each cam in accordance withthe period of the pulses. ihe cam discs are further provided with camportions E'ib and 55?), respectively, which have a constant radiusrelative to the axis of revolution. The cam flanks. iila or 58a arelocated immediately behind the constant-radius cam portions 5??) or 58?)in the running direction of the cam disc (indicated by arrows). The camflanks 57a and 53a have a steeply declining radius.

Two movable switching levers and ii are pivoted by respective pivot pins55 and it. Each lever is biased by springs, such as the spring assemblyshown at 53 and 5 so as to be urged from opposite sides against therespective cam discs 58 and 57. The switching levers have a feeler nose45b or ilb engaging the pertaining cam discs 58 or 5'1. Each lever isfurther equipped with a tappet portion 45a or 47a. During revolution ofthe cam discs 5'1, 58, the levers oscillate about their respectivepivots, and the tappets 46a and 47a actuate a movable part 48 of a pulseswitch in mutually opposing directions, the actuation being effectedeach time one of the levers 46 and 4'! drops along one of the cam flanksto its active position.

The movable part d8 of the pulse switch is pivoted on a pivot pin ll andcarries a contact control piece as of insulating material. In oneposition of the movable switch part, the insulating piece 45 separatestwo stationarily mounted con tact springs as with a contact 52. Mountedon the peripheral end of the movable part 38 is a detent sea whichcoacts with a roller 5i movably journalled on a leaf spring 52, thusproviding a snap action. The pulse contact device, therefore, operatesas a snap-action switch. The stationary contact springs 55 are mountedon one leg of a U-shaped stationary holder 56 so that the position ofsprings 55 relative to the movable switch part is may be adjusted bymeans of a set screw 59 screwed through the other leg of holder 56.

The above-mentioned locking means for alternately locking one of the twoswitching levers =35,

*4! while simultaneously releasing the ether lever under control by thepulse-wise reciprocating switching member #33, comprise a teeterrevolvable about a pivot pin 55. The two arms 45a and 45b of the teeterare linked to respective locking rods and (ii guided for longitudinalshifting motion. A third arm 450 of the teeter is straddled by a fork ddmounted on the mechanical switching member 43. During reciprocatingmovements of the member 43, the locking rods 66, Bl are alternatelyshifted in their axial directions so that in each of the two endpositions of member 48 one of the respective rods is placed in front ofthe pertaining switching lever 45 or t? thus locking the lever while atthe same time the other rod is withdrawn from the pertaining lever thusreleasing that lever.

The cam discs 5? and 58 are so positioned relative to the cycle ofmovement of the control elements (pulse control disc it) that thealternate release of the switching levers 56 and :1 occurs in aninterval of time in which the feeler nose of the one switching leverbeing released at a time comes into the range of the constant-radius camportion 5??) or 581) preceding the cam flanks.

It will be understood that the keys iii and the above-described elements4!, 43, 45, as, ii, 48 are all movably mounted on a common stationaryand rigid frame structure (not shown) on which the shafts i3, it arerevolvable and the locking rods 55, ii are slidable, and which alsocarries the spring means 53, 5d, the holder and the contact springs 55.

The operation of the apparatus is as follows. When key iii is beingdepressed, feeler pin 42 of feeler member s! is moved into the camgroove 27, and the same key operation causes the pulse control cam Hi toturn one revolution at constant speed, whereafter the feeler pin 42 isreleased to return into its original position. During the revolvingperiod of pulse control cam i l, the feeler member ii, tracing with itspin 32 the groove contour, moves back and forth and imparts itsoscillations through arm aid to the switching member .3 common to allpulse control discs. Assume that member i3 just starts moving from itsillustrated position in the clockwise direction and that this is tocommence the issuance of an individual current pulse. The clockwisemovement of member 53 is imparted through fork M and arm 450 to teeterHence teeter E5 oscillates accordingly. It withdraws the locking rod 55from switching lever 5 thus releasing this. lever. At the same time theteeter 45 advances the locking rod 5% thereby locking the switchinglever ll. The released switching lever 55, under its spring bias, hasits feeler nose 55b pressed against cam disc 5? at a point within therange of one of the cam portions 571). As soon as the feeler nose 45?)reaches the range of the next following cam flank 55a, this being thecase when the cam disc 5? has turned a corresponding amount in'theclockwise direction, the switching lever is reaches its active conditionrelative to the pulse contact device. That is, the switching lever 65,when dropping with its nose 3512 along the cam flank, continues movingunder its spring pressure so that tappet 460. tips the snap-actionswitch part %3 thus opening the contact 52 and establishing the nocurrent condition. The switch part 48 is held in this switchingcondition by the resiliently mounted roller 5i, while the switchinglever diiduring the further revolutionofcam disc 57, is returned to itsoriginal position.

In an analogous manner, the switching lever 41 is effective to actuatethe movable switch part 43 in the opposite direction, again undercontrol by feeler member 4| and pulse-control disc M. The ieeler nose41b of lever 4! slides on a constant-radius portion 58b of cam disc 58until the next-following cam flank 58a is reached. At this moment, thetappet 41a of switching lever 47 tips the switching element 48 to theother position thus establishing the current condition. Cam 5?,therefore, always controls the start of a current pulse, and cam 58always the end of the pulse.

The cam discs 51 and 58 are arranged on shaft IS with such a mutualangular displacement that the two cam flanks successively scanned firston one and thereafter on the other cam during each full reciprocation ofswitching member 43, are spaced apart a distance corresponding to thelength of the individual pulse. The cam discs 51 and 58, preferably, areangularly adjustable relative to each other on shaft I8 so that themoment when the switching levers reach the active condition may beadjusted relative to the cycle of movement of switching member 43. Thispermits advancing or retarding the operation of the pulse contact deviceso that the pulse duration may be adjusted within given limits. If thecam discs 51, 58 are arranged on the shaft 83 common to the pulsecontrol disc I4, i. e. if shafts l8 and I3 are integral orinterconnected, the cam discs 51, 58 are preferably also adjustableangularly with respect to the pulse control cams. The angular setting ofthe discs can then readily be calibrated so that each switching leverwhen released always drops first upon one of the cam portions 511) or58b of constant radius.

It is apparent that, with a constant revolving speed of the cam discs 51and 58, the current pulses being issued by the contact device have aconstant pulse duration and constant pulse periods regardless of anyinaccuracies with which the pulse control discs may be affected withincertain limits. These limits are determined by the length of theconstant-radius portions 5'") and 58b of cam discs 51 and 58. No matterhow large any time error in the stroke imparted to the switching member43 may be, the desired pulse correction is always obtained, provided thefeeler nose of the switching lever then being released will drop intothe range of one of the constant-radius cam portions 51b or 58b. Thiscondition, however, can be met without much efiort.

In conjunction with the improvement in pulse transmission, it issignificant that the number of the corrective cam discs need not, likethat of the pulse control disc, correspond to the total number of codecombinations, but that only two cam discs 51, 58 of high accuracy areneeded for any number of pulse control discs [4 of lesser accuracyrequirements. Besides, the exteriorly cammed discs can be more easilymanufactured than the pulse discs with lateral grooves.

The pulse contact device, of course, may also be designed as a reversingswitch to make the teletypewriter applicable for double-current(plus-minus) operation.

I claim:

1. Apparatus for transmitting current-pulse combinations, particularlyin teletypewriters, comprising selectively operable control means, amechanical switching member reciprocable between two positions undercontrol by said control means in accordance with the pulse combinationhaving cam flanks mutually spaced on the disc periphery in accordancewith the pulse cycle periods, two movable switching levers engageablewith the cam periphery of said responsive discs, said contact devicehaving a movable switch part, and said levers having respective meansengageable with said part for controlling said part in mutually opposingdirections when the respective switching levers are controlled by saidrespective discs to move to an active position, and locking means havingan element in engagement with said switching member and beingselectively engageable with one of said respective levers foralternately locking one of said respective levers and releasing theother lever in accordance with the reciprocation of said switchingmember, each of said levers when released by said locking means being insaid active position when entering into the range of one of said camflanks.

2. In pulse-combination transmitting apparatus according to claim 1,each of said cam discs having cam portions of a constant radius relativeto the axis of cam revolution, and said flanks being located directlybehind said respective cam portions in the direction of cam revolutionand having a steeply diminishing radius.

3. In a pulse-combination apparatus according to claim 2, said two camdiscs having, relative to the cycle of movement of said control means, aphase adjustment wherein each of said switching levers at the releasemoment engages the starting point of one of said constant-radius camportions ahead of one of said flanks.

4. In a pulse-combination apparatus according to claim 3, said controlmeans comprising pulsecontrol discs having a common shaft on which saidpulse-control discs are firmly mounted, said cam discs being alsomounted on said shaft and being angularly displaceable relative to eachother and relative to said pulse-control discs, whereby the moment whensaid levers reach said active position may be displaced relative to thereciprocating period of said switching member in order to adjust thepulse duration.

5. Pulse-combination apparatus according to claim 1, comprising springmeans engaging said respective switching levers and having on saidlevers a force directed toward said respective cam discs so as to actthrough said levers upon said movable contact piece when said leverspass over one of said cam flanks.

6. Pulse-combination apparatus according to claim 1, comprising springmeans urging said levers toward said respective cam discs, said lockingmeans having a teeter coupled with said switching member to rock whensaid switching member is reciprocating, two axially displaceable lockingrods linked to opposite sides of said teeter and alternately positionedon the cam-disc side of said respective switching levers for lockingsaid levers.

7. In a pulse-combination apparatus according to claim 1, said contactdevice having snap-action means joined with said contact piece.

OTTO MOSER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,394,765 Hagelin Feb. 12, 1946 2,522,461 Potts Sept. 12, 1950

